With rapid advancement of the fabrication technology of thin film transistor liquid crystal displays (TFT-LCDs), the LCD is largely applied in various electronic products such as a Personal Digital Assistant (PDA) device, a notebook computer, a digital camera, a video camera, and a mobile phone due to the fact it has advantages of smaller size, lighter weight, lower power consumption and low radiation. Moreover, since manufacturers aggressively invest in research & development and employ large-scale fabricating equipment, the quality of the LCD is unceasingly improved and the price thereof is continuously decreased. That promptly broadens the applied fields of the LCD.
Referring to FIG. 1, it shows a sectional view of a thin film transistor formed on a glass substrate in the prior art. The manufacturing process for the thin film transistor includes firstly forming a gate metal film on the glass substrate 10, wherein the gate metal film is made of aluminum or aluminum alloy material and is formed by sputtering deposition; then performing a first photo engraving process (PEP) for the gate metal film to define a gate structure 12 and metal line structures (not shown); subsequently covering the surface of the above-mentioned structures with an insulating layer 14 by a CVD process; sequentially forming a semiconductor layer 16 and a doped semiconductor layer 18 above the gate structure 12; afterwards, performing a second PEP for the semiconductor layer 16 and the doped semiconductor layer 18; subsequently forming a source/drain metal film on the doped semiconductor layer 18 and the insulating layer 14, wherein the source/drain metal film is a composite metal film made of a tri-layer metal molybdenum/aluminum/molybdenum and is formed by a CVD process; then performing a third PEP to respectively define a source structure and a drain structure 20 on the metal film and thus to define the thin film transistor on the surface of the glass substrate.
A cleaning procedure is further included in the steps of the above-mentioned process, especially the cleaning procedure performed before a photoresist is coated on the metal film of the glass substrate during the first and third PEPs. The cleaning procedure is used to remove particles of oxides and organics remained on the surface of the metal film so that coated photoresist patterns will not result in defects or disconnections. Furthermore, the organic residuals also reduce the adhesion of the photoresist to result in peeling. Hence, to the fabrication process of the THT-LCD, the cleaning process is one of the most important factors for process yield.
Referring to FIG. 2, which is a schematic diagram of a conventional scrubber before the glass substrate is coated with the photoresist, a scrubber 21 of the fifth generation TFT-LCD is exemplified. During cleaning the glass substrate 22, a delivering band 23 is used to transport the glass substrate 22 to a rinse unit 24. Three clean water nozzles 25 mounted on the top of the delivering band 23 at the rinse unit 24 are used to rinse out the glass substrate 22. After completion of rinsing, the glass substrate 22 is transported out by the delivering band 23. The rinsed glass substrate 22 is under a dry treatment with an air scraper 26. The clean water nozzles 25 are respectively connected to a deionized water supply source 27 with pipelines and rinse the glass substrate 22 in a manner of high pressure spraying in combination with a mega sonic wave. Moreover, a recycling pipeline 28 further disposed below the rinse unit 24 can recycle excess deionized water from the clean water nozzles 25 during the glass substrate 22 is rinsed.
However, the conventional scrubber and the cleaning method thereof cannot remove the organics and oxides on the surface of the metal film of the glass substrate and the formed photoresist patterns still have defects, disconnections and peelings. Therefore, those skilled in the art of photoelectric related industries endeavor to research and develop processes as well as to improve equipment so as to provide a method which can remove the organic and oxide residuals from the surface of the metal film of the glass substrate and solve the problems of the prior art.